TEA CO_2激光在AgGaSe_2晶体中的倍频实验研究

Experimental Research on the Second Harmonic Generation of TEA CO_2 Laser in AgGaSe_2 Crystal

实验上实现了TEACO2 激光在AgGaSe2 非线性光学晶体中的倍频光产生。着重研究了TEACO2 激光的能量、脉冲重复频率以及基波的焦点位置对于倍频光输出的影响。实验中得到了倍频光的角度调谐曲线 ,将入射光聚焦在晶体的中心区域 ,获得最大倍频光输出能量为 1 32mJ。脉冲能量转换效率为 2 4 % ,主脉冲的最大转换效率为 4 %。还分析了脉冲重复频率的变化 ( <10Hz)对倍频转换效率的影响。实验结果发现抑制倍频转换效率的主要因素为晶体的光学质量、激光脉冲低功率密度的拖尾以及激光脉冲的不稳定。特别由于脉冲附带长的拖尾加剧了热透镜效应 ,使得脉冲重复频率的增加引起转换效率的降低。

In this paper, the second harmonic generation (SHG) of the TEA CO 2 laser in an AgGaSe 2 nonlinear crystal is realized. How energy of TEA CO 2 laser, repetition frequency of pulse and focal position affect SHG is studied emphatically. The tuning curve upon incident angle is obtained and the maximal second harmonic energy 1.32 mJ is measured with the energy conversion efficiency 2.4% for total and 4% for main peak. Besides, the influence of pulse repetition rate (<10 Hz) on SHG conversion efficiency is analyzed. From the experimental results, it is found that the main factors restraining conversion efficiency are the crystal′s optical quality, the low power intensity tail of lasing pulse and the instability of pulse radiation. Specially, the thermal lens effect is intensified due to the long tail attached to pulse, which leads to decreasing of conversion efficiency if pulse repetition rate is enhanced.